Attachment plug cap



y 5, 1932- G. w. LIEBERUM ATTACHMENT PLUG CAP Filed Feb. 24, 1950 Inventor. Geovge W Liebewum. 1:33; I wQ w/ His Abtornqg.

Patented July 5, 1932 UNITED STATES PATENT I orrica GEORGE W. LIEBERUM, OF STRATFOBD, CONNECTICUT, ASSIGNOR TO GENERAL ELEC= TRIO COMPANY, A CORPORATION OF NEW YORK ATTACHMENT PLUG CAP to an improved means for securing the con tact elements to the cap without the use of screws or equivalent devices.

For a consideration of what I believe to be novel and my invention, attention is directed to the accompanying description and the claims appended thereto.

In the drawing which is illustrative of my invention, Fig. .1 is a perspective view ofa cap; Fig. 2 is a view'of a cap with certain of the parts broken away; Fig. 3 is a perspective view of a contact element, and Fig. 4; is an exploded bottom plan view of the cap and contact elements.

The cap or body 5 may have any suitable contour. As shown, it is cup-shaped having a well rounded upper part 6 and a cylindrical lower part 7 In the center is an opening 8 to receive the circuit wires which are )attached to the contact elements. The body is cut away on its under side to form a cavity 9,

the peripheral wall of which is defined by the part 7. 'The bottom wall of the cavity is flat or has flat areas perpendicular to the axis of the body to form seats 10 for the contact elements of which there are two arranged in parallel relation.

In the bottom wall of the cavity are rela tively deep and narrow recesses 11, one for each contact element, which are parallelto each other. In addition there are four recesses 12 which communicate with the central or wire receivin opening. These recesses are preformed in t e sense that they are made when the base is molded. They have straightsided smooth walls initially, which later frictionally engage and hold the contacts in place. As will be seen the recesses 11 are located at a greater distance from theaxis of the cap than the recesses 12 so that in efiect there are provided inner and outer recesses, the former being closed except at the surface of the seat and the latter being open along one side. In this manner two sets are-provided, each comprising three recesses, to form parts of a' three point anchoring means for each contact element, as willappear later. 13 indicates shallow holes to receive the inner ends of the wire binding screws 14 when the latter are seated to clamp the wires.

The body of the cap is made of suitable moldable insulation material or composition and is molded in one operation either by a hot or'cold process. The material should be rela tively hard and tough,--capable of withstanding considerable compression pressure without cracking and capable'of withstanding ordinary usage without injury. There are various moldable compositions available for the purpose.

Both-contact elements are alike, each being punched from brass or equivalent material. Each contact comprises a base 15\of considerable area which rests on a seat 10 and is provided with an extension 16 to receive a circuit wire and a binding screw therefor and three angularly displaced prongs 17, 18 and 19. Extending at right angles to the base is a contact blade 20. The prongs form a three point attaching means for the element. Of these the prong 17 is situated at the outer edge of the base and is wider than the others and is of such dimensions as-compared with those of the recess 11 that it willmake a forced fit therein when pressed or wedged into place. Usually it will be desirable to have the corners of the prong cut into the base material. The side edges of the prong may be serrated or roughened at 21 to ali'ord a better holding means when pressed or wedged into place. The prongs 18 and 19 located at the inner edge of the base are relatively narrow and after the element is mounted on its seat are forced or wedged'into the recesses 12. It is desirable to make these prongs slightly wider at their outer ends than at the point of con nection to the base 15 so as to form in efl:'ect a dovetail. As the corners or edges of the prongs are sharp they will cut into the walls of the recesses during the binding operation and slightly enlarge the inner ends thereof,

thereby improving the anchorage. The feature of utilizing the edges of the prongs to cut the side walls of the recesses to formv dove. tails is desirable because it is difficult to form dovetails during the molding operation of the proper proportions. The fact that the recesses 12 open into the central opening 8 afi'ords suitable space for the insertion of a tool to force or wedge the prongs into the recesses. By using three prongs the contact members or blades are not only firmly an chored in their respective positions but are also securely held against twisting.

The contact elements may be assembled in place'bya suitable fixture or means arranged to simultaneously insert the prongs 17 and bend the prongs 18 and 19 or the prongs 17 may first be inserted in the recesses 11 by one operation and the prongs 18 and 19 bent and forced into place by a second operation.

My improved construction has the advantage that it obviates the use of small parts such as metal inserts molded into the body of the cap and also of screws which parts are liable to work loose during ordinary'use of such cap. The contact elements may be made by suitable punch and die operations and the assembly is simplified and reduced in cost by reason of the absence of numerous small parts.

What I claim as new and desire to secure by Letters Patent of the United States, is

1. In a device of the character described, the combination of a body of molded'insula tion having a seat formed thereon, a central opening to receive circuit wires, and preformed outer and inner recesses located at different distances from the axis of the plug, a contact element having a base which rests on the seat and has prongs thereon inserted into said recesses after they are formed and frictionally retained by the walls thereof.

2. In a device of the character described, the combination of a body of molded insulation having a seat formed thereon, a central opening to'receive circuit wires, and two sets of preformed recesses of three each with contact elements each comprising a base, a contact blade, and three prongs which are inserted into a set of recesses and frictionally retained by the walls thereof. v

3. In a device of the character described, the combination of a body of molded insulation having a seat formed thereon, a central opening to receive circuit wires, and outer and inner recesses, the inner recesses opening into said wire receiving central opening, and contact elements each having a base that rests on a seat, a contact blade extending at right angles to the base, and prongs integral with.

the base and on opposite sides of it and of the blade which are inserted in the inner and outer recesses and frictionally retained by the walls thereof.

4. In a device of the character described, thecombination of a body of molded insulation having a seat formed thereon, a central opening to receive circuit wires, and a pair of outer preformed recesses, and four inner preformed recesses arranged in pairs and opening into the central wire receiving opening, and a pair of contact elements each having a base, a contact blade and three prongs, one of which is inserted into an outer recess and the others into a pair of inner recesses, all of said prongs being frictionally retained by the walls of the recesses.

5. In a device of the characterdescribed, the combination of a body of molded insulation having seats formed thereon, a central opening to receive circuit wires and sets of inner and outer preformed recesses, the inner recesses openin into the central wire receiving opening an contact members each having a base, a-contact blade extending at right angles thereto, a prong on the outer edge of the bast which is inserted into one of the outer recesses, and a prong on the inner edge of the base havin an enlarged outer end which is inserted lnto one of the inner recesses, said prongs being frictionally held by the walls of the recesses.

6. In an attachment plug cap, the combination of a base of molded insulation having a seating portion, a central opening to receive circuit wires and preformed straight-sided recesses, two of said recesses being located at a greater distance from the axis of the plug than the others, a pair of contact blades each having a base resting on the said seating portion and three angularly spaced prongs inserted in said recesses and frictionally retained by the walls thereof, said prongs holding the contacts against longitudinal movement and also preventing them from twisting one with respect to the other.

7. In an attachment plug cap, the combination of a base of molded insulation having a seating portion, a central opening to re ceive circuit Wires, and preformed straightsided recesses arranged in sets, one for each contact, contacts each comprising a blade, a

base and prongs integral With the base, one of said prongs having serrated edges and another having an enlarged outer end, said prongs entering the recesses and being frictionally retained by the Walls thereof.

In witness whereof, I have hereunto set my hand and seal this twentieth day of February, 1930.

GEORGE W. LIEBERUM. 

